Extension and retraction device.



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A. SIEWERT.

EXTENSION AND NBTRAQTION DBVIGB.

APPLICATION FILED APB. 6, 1911.

Fig. 2.

lll/[11111 A Laxman smwnar, or BERLIN, GERMANY.,

ExTENsI'oI; Np nnTnAcTIoN DEVICE.

To all whom t may concern:

Be it known that I, ALEXANDER SIEWERT,

` a subject of the King of Prussia, and residingatBernburgerstrasse24-25 Berlin, Germany, have invented certain new and useful Improvementsin Extension and Retraction Devices, of which the 'following is ayspecification.

This inventionrelates to a' mechanism for the extension of telescopingmasts and 'other extensible and retractable supports and liftingapparatuses.

It consists in causing the separate telescoping parts provided withinternal threading to be extended consecutively upona spindle placed inthe interior of themechanism.

Apparatuses are already known in which platforms and the like are raisedby turning spindles.A It'has` nevertheless not previously been possibleto construct in `this manner masts and the like the length of which4considerably exceeds twice the lengthv of the lifting spindle.- By thepresent invention, masts andthe like can be extended' by aid of aspindle the length of which need only `be a fraction of the height ofthe extended mechanism.

The invention is illustrated in the drawing in two figures, of which-'-Figure 1 is a longitudinal elevation, and Fig. 2 a section on the lineA-.A of Fig-1.

The telescopic parts b, Z2 and b are arranged in a casing c and theirextension is effected by means of a spindle a revolubly supported `inthe foot'of the casing, which spindle has a rather greater length thanthat of eachseparate tube.`- The lower part of the spindle is withoutthreading. The tubes :are provided at their lower end with internalthreading, which Vwith the exception of the'innermost tube b is out ofengagement with the spindle threading when the mast is retracted. Onturning'the spindle a by .means of the threading e, first the innermosttube b is raised, until it strikes with an -annular projection f againstthe projection g'of the tube bsurrounding it. It then Carries this tubewith it so that the matrix thereof engages with the spindle a and thenleaves the spindle inasmuch as it has been bolted to the aforesaid tubeZ2 by means of an automatic locking device. For this purpose, holes hare provided in V,the tubes, which coincide with one another when thel',Siieiileation ofy Letters Patent.

.application ma april a. 1'911.

Vlatam-.toa sept. 16. 1913.

Serial No. 618,361.

-lower projection f of the then inner tube of the tube surrounding it.On the tubesis placed in slot z' a pin 7c which is pressed into thecoinciding holes I1, by a spring l as soon as the head of the pin lo hasquitted the slot m.

In order that the rising telescopic part may not carry with it the othertelescopic part surrounding it by aid of friction, there is passedthrough all the parts, with the exception of the innermost, a pin a3,the inner end of which is rounded ofi". The rising tube presses this pinby means of its projection f\ outward to the extent of the thickness ofone tube and thereby liberates the tube immediately surrounding it. Thetelescopic parts may have a circular or polygonal section, and the tubewalls may be composed of net work.

The arrangement according to the present invention is adapted especiallyfor the construction of jacks especially for automobiles for the purposeof which a corresponding diminution of the height dimensions must takeplace.

The spindle a instead of being revolubly supported in a casing c can berigidly connected therewith and then by revolving this casing thespindle can be turned and thereby the extension of the telescopic partsbe effected. In this case the casing c is' preferably supported by ballbearings upon a separate bed plate and moreover provided with spokes orwith holes for the insertion of bars. v

I-Iaving now particularly described and ascertained the nature of...mysaid invention and in whatmanner the same is to be performed, I declarethat what I claim is:

A device of the kind described comprising in combination an outercasing, a number of telescopic parts in said casing, .a screw spindleplaced in the interior of said telescopic parts, means for rotating saidscrew spindle, a female screw at the bottom-end of each ofsaidtelescopic parts and adapted to engage the screw-threaded portion ofsaid screwspindle, a spring-governed bolt at the upper end of each ofsaid telescopic parts adapted to engage a hole in the adjacent innertelescopic part before the latter leaves the top of said screw-spindle,means for disengaging said spring-governed bolts when said telescopicparts are retracted, and a spring governed bolt connected with saidcasing In witness whereof I have hereunto'signed and adapted toprojectt-hrongh all sald telemy name this 23rd day of March 1911, inscopiopart-s with the exception of the innerthe presence of twosubscribing witnesses.

most and to be pressed outward by the ris- ALEXANDER SIEWERT. 5 ingtelescopic part to the extent of the thick- Witnesses:

ness of one of said telescopic parts, sub- HENRY HASPER,

stantially as set forth. WOLDEMAR HAUPT.

